1. Field of the Invention
The present invention relates to an optical disk drive that reads data from and writes data to an optical disk.
2. Description of the Related Art
When data is read from or written to an optical disk having a surface deviation, i.e., a slightly inclined disk surface, the number of disk revolutions should be lower than in the case of a normal disk (see Patent document 1).
[Patent document 1]
Japanese Patent No. Hei 10-188464
A surface deviation of a disk is detected by monitoring a focus actuator signal or a focus servo signal. However, since the focus actuator signal and the focus servo signal are corrupted by noise, the focus actuator or focus servo signals should be repeatedly measured and averaged. Additionally, when the surface deviation is large, detection thereof should be performed after a seek operation is terminated. As a result, it takes much time to detect the surface deviation after the disk is loaded into a drive.